By this you mean replacing a JCL with an REXX exec OR you just want to make it an online process..? If you just want to make it online then-
Try foreground menu in ispf, you will figure out how to use it, it is pretty easy and readymade to serve your requirement.
If you want to write a REXX, it should not be that hard using, CALL to IGYCRCTL and HEWL/IEWL with proper DD setup.
But make sure you use your site specific standard method/parameters.
manihcl85, I think you are just suggesting to automate submission of compiler JCL, and OP wants to replace JCL...